Need tips on tack welding the countershaft sprocket

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Well, the 6 splines on the countershaft are now half worn so it maybe time to tack a new sprocket before it shears whats left. The motor and trans are fine so a complete teardown seems premature at this point just to replace the shaft.

I have a 110v mig welder and an oldschool 220 arc welder, just not sure which would work best for the job. It would be nice to be able to grind the welds back if needed to replace the spocket at a later date so the weld placement and penitration are a concern.

Another thought is how to make sure the sprocket is squarly placed so it doesn't wobble. Any ideas are appreciated.

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The welds need to have real strength. Think of how much sheer strength even half worn splines have, and you need to add enough weldment to significantly strengthen it.

If you want to grind the welds back off in the future, maybe try not to get any penetration between the sprocket and shaft. Instead get weld strength from the size of the fillet weld bridging the two. Maybe even make a small O ring shaped piece of copper or aluminum that will fit right against the interface of the sprocket and shaft, to stop any weld from getting in.

And of course you can't build much heat in the shaft or you'll de-temper it and cook the oil seal in the case. Maybe stitch together many short beads, with plenty of cooling time between.

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I tried this a few years back before I split the cases and put a new shaft in. It all depends how you ride as the whether the weld will hold. Mine never held more than one ride. I ride a lot of rocky trails. I now use the slightly wider xr650r sprocket. I clean and grease the splines after a muddy ride or every 1000 miles or so. I also put a new sprocket on every year as to keep the tolerances tight on the splines and prevent to much slop which will lead to premature wear on the shaft. I now have 4000 miles on the shaft and no wear, looks like new.

Edited June 1, 2014 by jtf1307tie

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The wonderful human being that I bought my bike from goobered on the sprocket like you are considering. I did not realize it at the time of sale, but did a few weeks in when I went to install new spockets and chain. I ended up riding the bike for a full summer and tore it down over the winter to replace the shaft.... so it can be done. Mine was still going strong when I ground off the weld.

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6010 dc reverse. 4 sides so you can grind off to remove to replace shaft later. not as much shear strength as7018 but more penetration and fast freeze. makes grinding off later easier and may hold longer. cool with water or wet rag immediately. keep the heat to a minimum to avoid frying the seal on the shaft. im on my 3rd shaft. so far, the xrr sprocket is the cure.

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As usual will make a few ripples in this pond..... you do a botch job, it goes wrong and you do more damage. If a jobs worth doing it's worth doing correctly - split the case, new shaft and use a 650r sprocket......

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Unfortunatly my 1990 has only 6 splines and there is no sprocket similar to the 650R that I know of. Yeah I know spliting the case is the proper way to go and I would if she was tried ,missing shifts, sticking in gear and so on. Just trying to put off the enevitable right now. (Heck I don't even know if the shaft is still available for a 90.)

Several spot globs with cooling between welds seems the way to go. With 1/2 the spline left maybe tack it with the sprocket turned tight to the acceleration side to prevent the greatest shear. At this point even if the welds break it will still make it back home. Not sure yet how the stock keeper will fit into the process though.

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The new XR600 and XRL countershafts will work just fine in your engine, so you can easilly get a replacement shaft. Use an XR600 shaft as it has the back end of the shaft machined to accept the kickstart idler gear... the XRL shaft is not machined.

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Definitly would need the machined shaft for the kickstarter, is that an OEMHonda part? The 6 spline made it 24 years, 40,000 miles with little attention (until I read the CS topics here) so that would be the option, heck I'll be pushing 80 or daisy's by then anyways.